Many surgical procedures have been developed involving the replacement of a knee joint with a prosthesis. Examples of such procedures are disclosed in the R.M.C..TM. Total Knee System technical manual published by Richards Manufacturing Company, Inc. of Memphis, Tenn. and the Surgical Procedure for the Whiteside Ortholoc.RTM. Modular Knee System Manual, published by the assignee of the present application. Each of the surgical protocols details the steps of exposing the knee joint and then preparing the distal femur and proximal tibia to enable the implantation of the prosthesis.
The alignment of the total knee components is an essential step in the performance of the total knee replacement arthroplasty. The article of R. S. Laskin, Orthopedics, January 1984, Vol. 7 No. 1, pp. 36-46, details various alignment systems, and an indepth discussion of the orientation of the knee joint and the criticality of the prosthesis reflecting an accurate varus or valgus angle for proper prosthesis placement.
Various instruments have been used to assist in alignment of the various distal cuts and anterior/posterior cuts made during the preparatory steps discussed above. For example, the U.S. Pat. No. 4,474,177 to Whiteside, issued Oct. 2, 1984 discloses a method and apparatus for shaping a distal femoral surface. The patent discusses a femoral surface modifying instrument in the form of a distal femoral condyle cutting guide. The U.S. Pat. No. 4,487,203 to Androphy, issued Dec. 11, 1984 discloses a single guide member for use in resecting the distal femoral condyles, the proximal tibia, and the distal femur. The surgical procedure entitled "Knee Replacement Using the Insall/Burstein Total Congular Knee System, issued by the New York Society for the Relief of the Ruptured and Crippled Children, Zimmer Orthopedics, Warsaw, Ind., discloses an operative procedure utilizing a spacer guide and a further cutter alignment instrument.
Each of the above patents and protocol provide alignment instruments which do not have the capability of axially and angularly aligning all preparatory instruments based on a single point which could thereby totally coordinate all preparatory cuts prior to final insertion of a trial or final femoral prosthesis component. Accordingly, various cuts, planings, and final placements are performed by estimations and purely eyeball estimations of appropriate angles and axial displacements of cuts.
The present invention provides a device and method allowing for accurately cutting the femur to accept femoral prothesis by providing a single point reference device that locates along the long axis of the femur and locks to it for referencing the external device to accurately place the cuts.